Unit test coverage is a false comfort signal. Your actual problem is that you're testing implementation details instead of user flows.
Drop the obsession with component coverage. Focus on critical paths with e2e tests instead. Yes, they're slower, but you need maybe 15-20 well-written Playwright tests covering signup, payment, core features. Skip the rest.
For flakiness: use waitFor with explicit conditions, not arbitrary sleeps. Stabilize your selectors with data-testid attributes. Run e2e tests serially in CI if you're sharing state. Most "flaky" tests are actually environment problems, not test problems.
The real win is accepting that frontend testing has different ROI than backend testing. Unit tests for business logic, e2e for user impact. Don't chase coverage percentages.